This invention is directed to electromagnetic force machines and, more particularly, to electromagnetic force machines suitable for performing non-destructive tests on and/or removing dents from a panel.
In the past, a variety of electromagnetic force (EMF) machines have been developed for use in the production and maintenance of panels to perform non-destructive tests on panel bonds and to remove dents. One such machine is described in U.S. Pat. No. 3,825,819 issued to Karl A. Hansen et al on July 23, 1974 and entitled "Dynamic Proof Loading of Metal Bond Structures Using Pulsed Magnetic Fields". Another such machine is described in U.S. Pat. No. 3,998,081 issued Dec. 21, 1976 to Karl A. Hansen et al, entitled "Electromagnetic Dent Puller". U.S. patent application, Ser. No. 646,068, filed Jan. 2, 1976, by Karl A. Hansen et al and entitled "Electromagnetic Dent Remover with Electromagnetic Localized Work Coil", and U.S. patent application, Ser. No. 752,755 filed Dec. 20, 1976 by Karl A. Hansen et al and entitled "Flux Concentrator for Electromagnetic Pulling" both describe improved flux concentrators for use in EMF machines.
While EMF machines of the type described in the foregoing patents and applications have been found to be well suited for performing non-destructive tests on panel bonds and removing dents from panels, they have certain disadvantages. Specifically, the power supplies utilized with these prior art machines have, in general, been massive and, thus, non-portable. Such power supplies have been non-portable because they have incorporated heavy components. In this regard, heavy oil filled capacitors were included to produce the power used to energize the flux concentrators. In addition to their weight, oil filled capacitors have the disadvantage that they produced power at voltages in the kV range (e.g., 10 kV), which is well above the level needed by flux concentrators. In this regard, flux concentrators require large currents (25,000 amps) not large voltages. As a result, large (3,000 lbs) transformers were required to reduce the oil filled capacitor voltage to a suitable level (to about 300 volts), while increasing the available current to the necessary level. The end result of this arrangement is a heavy (approximately 4 tons), stationary and inefficient power supply. Moreover, when additional voltage was required, additional oil filled capacitor banks were added to the already heavy power supply. (As will be better understood from the following discussion, the voltage required to produce a suitable slow current pulse in a single turn concentrator is higher than the voltage required to produce a suitable slow current pulse in a multiple turn concentrator.) Because prior art EMF machines and their power supplies have been heavy and therefore difficult to transport, in the past, parts have been brought to the location of the machine, rather than the machine being brought to the location of the part, as is desirable in many instances. For example, when it is necessary to remove dents from a panel of a part of a relatively large item, e.g., the flap of an aircraft, it is preferable to be able to bring the dent removal equipment to the location of the part, rather than remove the part and bring it to the location of the equipment, because part removal and reinstallation is usually a time consuming and expensive chore. Moreover, during the removal period of time, often the entire item (aircraft) is out of service. In other instances, it may be almost impossible to remove the part, e.g., a panel forming part of the fuselage of an aircraft is riveted in place and difficult to remove.
Therefore, it is an object of this invention to provide a new and improved electromagnetic force machine.
It is another object of this invention to provide an electromagnetic force machine suitable for performing different types of operations on panels and the like at their location.
It is a further object of this invention to provide an electromagnetic force machine that includes a universal portable power supply adapted to energize a variety of flux concentrators, each of which produces a magnetic field having a unique pattern.
It is yet another object of this invention to provide an electromagnetic force machine including a universal portable power supply suitable for energizing a variety of flux concentrators adapted to perform non-destructive tests and/or dent removal operations on panels and the like.